One unifying element of this program project is the use of Mycoplasma pulmonis-infected mice and rats as a model of chronic airway inflammation. All four projects will use this model to some extent in the proposed research. A small animal core will be established to meet this need. The ore has three main functions: (i) to standardize the infection procedures and handling of pathogen-free and infected mice and rats in the barrier facility; (ii) to maximize the efficiency and economy of housing and handling pathogen-free and infected animals; and (iii) to make pathogen-free and M. pulmonis-infect animals or tissues from these animals readily available to all of the investigators. The core staff will use tested stocks of M. pulmonis to ensure reproducible results and to minimize variability. The core staff will be responsible for husbandry and monitoring of pathogen-free and infected animals in the barrier facility, including the routine measurement of body weight, maintenance of sentinel animals, and periodic serological analyses. The core staff will also assist with some aspects of tissue harvesting, for example, bronchoalveolar lavage, flow cytometry, and tissue removal and fixation. Lastly, the core will assist in the breeding, colony management, and genetic analysis of various mutant animals stocks that will be used in the four projects. The core will build on an existing infrastructure that is already being used to generate M. pulmonis-infected mice and rats on a small scale. Centralizing and expanding the currently limited scope of the infection and maintenance process will avoid unnecessary replication of resources in the four projects. It will also ensure that common procedures are used by all of the groups and will, therefore, facilitate the exchange of information and foster collaborative interactions.